1. Technical Field
The present invention relates to a method of measuring the printing pressure between two cylinders of a printing machine. More particularly, the invention relates to a method of measuring the printing pressure between the ink transfer or blanket cylinder and the impression cylinder of a rotary printing press by using a force or displacement sensor disposed on or proximate to the impression cylinder.
2. Background Art
A control system of this kind is disclosed in Tappert et al., U.S. Pat. No. 4,351,237. The output signal of a piezoelectric pressure sensor mounted on the internal surface of an impression cylinder bearing is fed to a signal processing stage connected to a clock unit. The clock unit receives a signal proportional to the angle of rotation of the impression cylinder, and the measuring operation is controlled by the clock signal and a sheet movement control signal. In this fashion, the output signal of the pressure sensor is sampled according to the angle of rotation, but the sampling is performed only in the angle or phase range corresponding to the maximum printing pressure. The sampled value is compared with the set-value of a set-value transmitter in a discriminator for increasing or decreasing the printing pressure in response to the comparison.